I do have a problem when attempting to add custom configuration options to Transmission, however.

I'd like to increase the cache transmission uses from 4MB to 8MB.

I'm trying to do this by adding the following lines to the custom configuration box on the page nas-bittorrent

{
"cache-size-mb": 4
}

When that is added, transmission fails to start. I have tried adding a comma to the end after the 4, but this does not let transmission start either, so I think I may be entering the configuration wrongly.

It would be great if someone could tell me how to add a line to the custom configuration box.